Enhanced Photocatalytic Degradation of Methylene Blue by Using Au-TiO2

Abstract:

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In this work, Au-TiO2 nanoparticles (NPs) were synthesized in a single step by flame spray pyrolysis (FSP) method. X-ray diffraction (XRD) results indicated that phase structures of all samples TiO2 were the mixture of anatase and rutile phases. High resolution transmission electron microscopy (HRTEM) showed that dark spots of Au NPs deposited on larger TiO2 nanoparticles. HRTEM results indicated TiO2 NPs were average crystallite size in the range of 10–30 nm whereas the average diameter of Au NPs was about 5–10 nm. UV–Vis absorption spectroscopy technique showed peaks attributable of surface plasmon resonance (SPR) to Au NPs loaded on TiO2 in the wavelength of 500–630 nm. The Au-TiO2 NPs showed excellent photocatalytic activity for the degradation of methylene blue (MB) under UV-Vis irradiation. It was found that 0.25 mol% Au-TiO2 which was a better photocatalyst than others under the same reaction conditions. The results showed that Au NPs-loading could effectively improve the photocatalytic activities of TiO2.

Abstract: Sn-doped SiO2 thin films were fabricated on Si substrates by the Sol-Gel method.
Permanent refractive index change was found using ultraviolet (UV) laser radiation at 248 nm. The photoinduced refractive index change increased after radiation and variety in the contents of Tin. The optical and surface properties of the films were characterized using X-ray photoelectron spectroscopy (XPS) and variable angle spectroscopic ellipsometry (VASE).

Abstract: The underpotential deposition of hydrogen was studied in 0.5 mol dm-3 HClO4 solution
on an electrode based on Ebonex-supported platinum electrocatalyst spread on rotation Au disk
electrode (Ebonex/Pt). Pt catalyst was prepared by the impregnation method from 2-propanol
solution of Pt(NH3)2(NO2)2 and Ebonex powder. Ebonex support (nonstoichiometric mixture of
titanium oxides) was characterized by: X-ray diffraction (XRD), energy dispersive X-ray
spectroscopy (EDX) and BET techniques. The synthesized catalyst was analyzed by TEM
technique. Voltammetric profiles at the Ebonex/Pt catalyst surface in 0.5 mol dm-3 HClO4 aqueous
solution obtained at different temperatures with the evaluation of the temperature effect on the
reversible adsorption of the Hupd state are presented and the thermodynamic state functions for H
adatom adsorption process are calculated. The chemisorptive energy strength of the Ebonex/Pt-H
state is estimated in order to establish the relationship between the surface structure and the
electrocatalytic activity of Ebonex/Pt electrode and compare it to the one for smooth polycrystalline
Pt.

Abstract: Thin films of various composition in the system of TiO2•SiO2 have been fabricated by the sol-gel process using Si(OC2H5) and Ti(OC3H7i)4 as precursors. TiO2•SiO2 films were formed on the glass substrate by spin-coating technique and heated at 500°C for 1 h. The relationship between hydrophilicity, photocatalytic properties and self-cleaning property with SiO2 addition and UV light irradiation were investigated. Photocatalytic activity of TiO2•SiO2 films showed decomposition of ~97% of acetaldehyde in 2 h and a water contact angle of ~10°. TiO2•SiO2 films can have more hydrophilic activity and less photocatalytic activity by increasing of SiO2 addition. XPS measurements revealed that the amount of organic compounds adsorbed on the films decreased with the UV light irradiation and SiO2 addition, because of the increased of both OH group contents in films and decomposed organic contaminants of the films surface.

Abstract: Metal-organic framework composites RhB/MOF-5 have been successfully prepared by diffusion of solvent method for the first time. The investigations of LM, XRD, FT-IR, UV-Vis, and photoluminescence confirm the existence of RhB in the pores of MOF-5. The composites which show strong fluorescence and obvious red-shift compared with RhB in CHCl3 could be candidates for applications in optics, especially in laser systems.

Abstract: Different Mg-Al layered double hydroxide (LDH) nanomaterials had been synthesized using anion surfactant in the solution of mixed solvents. Using sodium dodecylbenzenesulfonate (SDBS) as morphology-controlling agent, different morphologies of Mg-Al LDHs are obtained successfully. The concentration of the reactant and the dosage of SDBS had significant effects on the morphology of the products. The morphologies of flower-like spheres, nanospheres, and micro-particles were efficiently obtained, respectively. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize these products.